Novel antiperspirant adduct compositions and process for making same

ABSTRACT

A process for preparing a submicron antiperspirant adduct. The process begins by dissolving a mixture of an aluminum-containing salt and a steric stabilizer in a solvent. The antiperspirant salt is then precipitated into the steric stabilizer. The resulting adduct of submicron size can be dispersed into a cosmetic carrier or otherwise processed.

BACKGROUND OF THE INVENTION

The present invention relates to adducts for use in antiperspirants, andprocesses for making and using such adducts.

Various antiperspirant formulations are well known in the cosmetic art.Certain ingredients of the formulation will always be present, whileothers will depend upon the particular form of the antiperspirant, e.g.,a stick, a gel, a lotion, or an aerosol. For example, sticks oftencontain an organic liquid carrier, a gelling agent that provides theantiperspirant stick with its solid character, and an activeantiperspirant ingredient. Antiperspirants are applied to an area of thebody such as the axilla by rubbing to deposit a layer of antiperspirant.Accordingly, it is desirable that the ingredients used in anyantiperspirant formulation result in an antiperspirant which is smooth,non-greasy and non-tacky.

Certain disadvantages exist with current formulations including the factthat a white chalky residue is often left on the body and transferred toclothing, and that the formulation can break down after storage, e.g., astick can shrink or become flaky and crumbly. A chalky residue after useof a stick antiperspirant is due in part to the fact that relativelylarge particles of the antiperspirant salt are employed in stickantiperspirants. Since the original stick itself is white, the depositon the skin is also white.

Accordingly, it would be desirable to produce antiperspirants which aretransparent or translucent as well as having the other desirableproperties for an antiperspirant. One factor which determines theoptical appearance of a dispersion formulation is the particle size ofany ingredient which is present in solid form.

The question of the effect of particle size upon optical appearance hasbeen investigated by the paint industry. To develop hiding power, apigment must be subdivided until the refractions, diffractions, andreflections produced by the many tiny particles are capable of reversingthe direction of light rays which strike the particles. The smaller theparticle diameter, the greater the number of individual particles in anyspecified weight or volume, and consequently, the greater the number ofpigment interfaces to interfere with the linear transmission of light.Thus, it might be expected that a pigment manufacturer would strive forthe smallest possible particle size to obtain the greatest possiblehiding power. However, it is also known that a particle disappearsoptically when its size has been sufficiently reduced.

Studies have shown that the ability of a particle of any given materialto scatter or to diffuse light of a particular wavelength is a functionof its particle size relative to that wavelength. Various estimates haveplaced the most effective particle diameter for hiding power atapproximately one-half the wavelength of the light involved. Therefore,as the diameter of a pigment particle becomes increasingly smaller thanone-half of the shortest wavelength of visible light, about 4,000angstroms for violet, it begins to disappear because it loses itsability to produce visible interference with the passage of light waves.

However, in the case of particles to be used in antiperspirant products,additional considerations must be taken into account when estimating theoptimum antiperspirant particle size needed to achieve clarity. Particlesize and particle population or concentration must be carefullybalanced. Since antiperspirant compositions require a very highconcentration of active ingredients as compared to the model systemsdescribed in the colloid scientific literature, the particle sizes toobtain optical clarity must not exceed about 0.20 micron and preferably0.10 micron.

Unfortunately, when such small particle sizes are used, other factorsbecome important, such as how to prevent such small particles fromagglomerating to reform larger particles that could no longer be suitedfor clear colloidal dispersions. While this area has been the subject ofa sizable amount of research, little success has been achieved and onlyvery few substances have been successfully made into stable colloidaldispersions. For example, Markovic et al, "Structural and DynamicFeatures of Concentrated Non-Aqueous Dispersions", Colloids andSurfaces, 24 (1987), 69-82, and "Small Angle Neutron Scattering Studieson Non-Aqueous Dispersions of Calcium Carbonate", Colloid and PolymerScience, 262 (1984), 648-656, describe colloidal dispersions of calciumcarbonate in toluene. The core particles of calcium carbonate arestabilized by an adsorbed layer of an alkyl aryl sulfonic acid.

Another study of this effect is an article by Mates et al, "StericStability of Alkoxy-Precipitated TiO₂ in Alcohol Solutions", Colloidsand Surfaces, 24 (1987), 299-313. That particular study was anexperimental program which evaluated the suitability of varioussurfactants as steric stabilizers for ethanol suspensions ofalkoxy-precipitated TiO₂ particles. The purpose of the study was todetermine the most suitable surfactants for preventing agglomerationand/or aggregation of the TiO₂ particles.

Before proceeding further, a definition of terms used in fine particlesize technology is in order. A particle is defined as a single unit ofmaterial which can be clearly discerned in a fine particle system eitherby direct observation or by light or electron microscopes.

Individual particles may be associated into agglomerates or aggregates.Particles in an agglomerate are only loosely associated while in anaggregate, the particles are held together strongly to form a ball orblock that acts as a distinct particle for all practical purposes.Therefore, an agglomerate is a loose confederation of particles that canchange when it is handled, whereas an aggregate is a strongly weldedassembly of particles that will maintain its group identity under normalhandling conditions.

A large number of particles, either agglomerated or aggregated or both,is said to constitute a powder. Generally a powder is regarded as beingconstituted of particles in the size range of approximately 0.1 to 1,000microns.

Particles less than 0.1 micron are normally dispersed in a vehicle andregarded as constituting a colloidal dispersion. If the vehicle isorganic, the dispersion is referred to as an organosol. In thedispersions covered by this invention, stability with the total absenceof flocs is mandatory. Flocs are clusters of low-strength agglomeratesand aggregates loosely attached to each other by Van der Waals forces.

The behavior of a powder system is determined by surface, inertial,gravitational, and other macroscopic forces. In a colloid, surfaceenergy, capillary attraction, and surface charges very frequentlydominate the behavior of the system.

Also, binding forces between particles start assuming considerableproportions as particle size decreases. This is an extremely importantconsideration when one wishes to attain optical clarity by means ofparticle size reduction because one must divide the antiperspirant saltto ultrafine size of 0.2 and preferably 0.1 micron or less, suspend theparticles in a vehicle, and keep the particles from regrouping to formagglomerates, aggregates, and flocs despite the extremely highparticle-to-particle adhesion energies that develop. Furthermore, anultrafine particle formed by any technique must never be allowed tocombine with a sister particle to form the various clusters aspreviously cited. Thus a particle must be stabilized immediately as itis formed by surrounding it with a protective layer or shell to shieldit from contact with another particle during collision. Thus, one mustnot only reduce the particles to an appropriate size, but must alsostabilize those particles.

Finally, two types of colloidal systems exist, viz: sols and gels. A solconsists of discrete, separate particles (normally solids) dispersed ina continuous phase (normally, though not necessarily, a liquid) andresembles a solution in many respects. A gel, however, comprises twocontinuous phases with one of them normally being a solid.

Accordingly, a need exists for a sol (organosol) of an antiperspirantsalt in a cosmetic organic liquid (e.g., an emollient or moisturizer)which is stable during storage even though it is made up of ultrafineparticles. A need also exists for an antiperspirant salt in particlesizes sufficiently small to be below the wavelength of light, i.e.,substantially below 0.4 microns, thereby resulting in transparency athigh concentration. Moreover, a need exists for a method for preparingsuch particles such that the particle size distribution initiallyproduced, and the distribution maintained over a period of time, aresufficiently uniform that the organosol retains its originaltransparency or translucency.

SUMMARY OF THE INVENTION

The present invention is a process for preparing a submicronantiperspirant adduct. The process begins by dissolving a mixture of analuminum-containing antiperspirant salt and a steric stabilizer in asolvent. The antiperspirant salt is then precipitated into the stericstabilizer.

The resulting material is a unique and novel adduct of submicron sizewhich can be dispersed into a cosmetic carrier or otherwise processed.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is a process for preparing a submicronantiperspirant adduct. Essentially, the process precipitates particlesof antiperspirant salt in submicron size, and as a part of theprecipitation, forms a protective shell of specific materials aroundeach particle to prevent agglomeration; this allows the particle toremain intact when the adduct is dispersed into a vehicle, thus forminga stable dispersion. The material which forms a shell around the productis referred to herein as a "steric stabilizer". One way to achievesteric stabilization involves the use of a material which has two ends,one of which has affinity and compatibility with the surface of theparticle to be coated, and the other of which is compatible with thevehicle used to prepare the dispersion.

The process used in this approach to obtain appropriate sized particlesis precipitation. The basic substance from which ultrafine particles aredesired, and the steric stabilizer, are dissolved in a suitable solventsystem, and then the basic substance is precipitated into the stericstabilizer. One means of accomplishing this result is to causeprecipitation by removal of the solvent, such as by evaporation of thesolvent to precipitate the original substance, or by freeze drying whenthe solvent is aqueous. In another embodiment which can be employed incertain instances, precipitation of the original substance into thestabilizer can be accomplished by addition of other materials to modifythe solubility parameter of the solvent system, followed by separationof the precipitate for further processing.

Essentially, the antiperspirant particle is precipitated immediately asformed into an oriented layer of molecules of the steric stabilizer,which layer surrounds the particle at all times to prevent clusteringduring collision. This layer of steric stabilizer is attached to thesurface of the antiperspirant particle by simple physical adsorption.

Stabilizers for use in the present invention must have well balancedproperties to exhibit compatibility with both components of theorganosol of the polar antiperspirant and the much less polar ornonpolar delivery vehicle. Typical vehicles are esters such as isopropylpalmitate, or volatile silicones. Hence the ideal stabilizer is amolecule having two moieties: one moiety highly compatible with thepolar antiperspirant and the other moiety compatible with a vehiclewhich is much less polar (an emollient ester) or non-polar (a volatilesilicone).

Those skilled in the art will recognize that various materials meet theabove criteria. Preferred materials are nonionic surfactants. Suitablenonionic surfactants are ones in which the hydrophilic moiety ischemically compatible with the antiperspirant salt, while the lipophilicmoiety is chemically compatible with the cosmetic carrier into which itis formulated. Typical nonionic surfactants for use in the presentinvention are ethoxylated alcohols, polyethoxylated alcohols, alkylphenol ethoxylates, sucrose esters, etc. The best results have beenobtained with ethoxylated fatty alcohols, i.e., surfactants derived byextending fatty alcohols with various levels of ethylene oxides. Many ofthe materials are commercially available and of approved cosmetic gradeand purity, e.g., stearyl, oleyl, and cetyl alcohols extended with fiveto forty moles of various alkylene oxides.

A surfactant which has been found to provide excellent properties isOleth-10 which is the polyethylene glycol ether of oleyl alcohol thatconforms to the formula:

    CH.sub.3 (CH.sub.2).sub.7 CH═CH(CH.sub.2).sub.7 CH.sub.2 (OCH.sub.2 CH.sub.2).sub.n OH

where n has an average value of 10. This material is availablecommercially from numerous sources as shown in the Cosmetic IngredientDictionary of the CTFA, including under the trademarks MACOL OA-10(Mazer Chemicals, Inc.; Gurnee, Ill.) and VOLPO 10 (Croda, Inc.; NewYork, N.Y.).

Suitable alkyl phenol ethoxylates include nonoxynol-8 and octoxynol-9(CTFA listed). A suitable sucrose ester is sucrose stearate.

As discussed above, in this technique the antiperspirant salt and thesteric stabilizer are both dissolved in a common solvent followed byprecipitation to leave the antiperspirant salt encapsulated in thissteric stabilizer which will remain in the final formulation of theantiperspirant.

Suitable solvents for the antiperspirant salt include water, alcohols,and combinations thereof. A preferred solvent is ethanol because it isreadily removed by evaporation to precipitate the antiperspirantparticles.

The ratio of stabilizer to salt only becomes important when a cleardispersion based upon particle size is desired. Otherwise, the lowerlimit for the stabilizer is a sufficient amount for a stable adduct toform, i.e., an amount sufficient to inhibit agglomeration, typically astabilizer to salt ratio of about 0.1:1, and the upper limit is basedupon the desired concentration of salt in the antiperspirant product, atypical maximum being about 3.0:1. It is desirable to minimize the ratioof stabilizer to antiperspirant to ensure a high concentration ofactives and a low concentration of additives in the end product. Even ifa small particle size is not desired, the present process isadvantageous because it provides high purity salt particles free fromthe decomposition products (like opaque aluminum oxide) obtained duringthe spray drying process. The conventional process of makingantiperspirant salts uses spray drying; the elevated temperatures ofthis process cause some decomposition of the salt to produce smallamounts of an opaque material which is believed to be aluminum oxide.

If a substantially clear dispersion is desired, then the minimum amountof stabilizer becomes important because a sufficient amount must be usedto stop crystal growth at the desired size range, i.e., less than about0.2 microns. In this circumstance the broadest range of stabilizer tosalt is 0.5:1 to 3.0:1. The preferred range is 0.75:1 to 2.5:1. A morepreferred range is 1:1 to 2.25:1. The most preferred range is 1.25:1 to1.75:1.

The adduct thus prepared is dispersed into a cosmetic vehicle such asemollient esters, e.g., isopropyl palmitate or isopropyl myristatewithout the need of a dispersing agent. In this case the stabilizerselected is also an effective dispersing agent because of the highaffinity of a part of its molecule to the vehicle. If desired, up toabout half of such esters can be replaced with a non-polar siliconefluid such as cyclomethicone without upsetting the compatibility ofvehicle and stabilizer.

Clear dispersions from the above adducts can be prepared withoutadditional dispersing agents as is usually required since the stericstabilizers are good dispersing agents; however, it was found that smallamounts of water are needed to produce the ultimate dispersion. Theminimum amount of water is that sufficient to provide the desired degreeof transparency, with the maximum amount of water being less than thatwhich would dissolve the antiperspirant salt. Typically, the water willbe between about 2% and about 7% by volume, more preferably about 3-4%by volume.

While not wishing to be bound by theory, it is believed that somethingmore than just particle size is involved in the transparency obtainableby the present invention. For one thing, a considerably higher ratio ofsurfactant is used than is employed in other systems, and for another,the dispersed adduct remains cloudy until water has been added.Accordingly, there appears to be a relationship between the water andthe stabilizer/antiperspirant salt adduct, in addition to therelationship between antiperspirant and stabilizer.

Substantially clear antiperspirant dispersions are defined in thepresent invention as follows: a dispersion of antiperspirant issubstantially clear if its % transmission at 515 nanometers is about 25or more (% transmission may be measured spectrophotometrically using a515 nanometer monochromatic beam of radiation and a specimen thicknessof two centimeters).

The antiperspirant component used in the present invention may be any ofthose which contain aluminum, either alone or in combination with othermaterials such as zirconium. Typical aluminum salts, although notall-inclusive, include:

Aluminum chlorohydrate;

Aluminum sesquichlorohydrate;

Aluminum dichlorohydrate;

Aluminum chlorohydrex PG or PEG;

Aluminum sesquichlorohydrex PG or PEG;

Aluminum dichlorohydrex PG or PEG;

Aluminum zirconium trichlorohydrate;

Aluminum zirconium tetrachlorohydrate;

Aluminum zirconium tetrachlorohydrex PG or PEG;

Aluminum zirconium pentachlorohydrate;

Aluminum zirconium octachlorohydrate;

Aluminum zirconium trichlorohydrex-gly;

Aluminum zirconium tetrachlorohydrex-gly;

Aluminum zirconium pentachlorohydrex-gly

Aluminum zirconium octachlorohydrex-gly;

Aluminum zirconium chloride;

Aluminum zirconium sulfate;

Potassium aluminum sulfate;

Sodium aluminum chlorohydroxylactate;

Aluminum bromohydrate.

In general the active antiperspirant component should be present in thesame amounts at which such materials are employed in prior artcompositions. As a general rule, the antiperspirant composition shouldcontain from about 5% to about 30%, preferably from about 10 to 25% ofthe active antiperspirant salt component.

A variety of liquid carriers are suitable for use: examples includeisopropyl palmitate; isopropyl myristate; phenyl silicone fluid; andcyclomethicone. The liquid carrier can also contain fragrances andcoloring agents as normally used in the art.

The amount of liquid carrier used should be sufficient to provide asuspension of the active antiperspirant ingredient; there is no upperlimit of the amount of liquid carrier used, other than the need to havethe necessary amount of active component. In general, the antiperspirantshould contain from about 40% to about 80% liquid carrier by weight.

For stick antiperspirants, it is necessary to use some gelling agent inthe antiperspirant. Suitable gelling agents are well known to thoseskilled in the art.

In order to further illustrate the present invention and the advantagesthereof, the following specific examples are given, it being understoodthat these examples are intended only to be illustrative without servingas a limitation on the scope of the present invention.

EXAMPLES

The following is a general procedure for the precipitation of anantiperspirant salt into a steric stabilizer via evaporation from analcoholic solution, and its dispersion into a cosmetic carrier, such asisopropyl palmitate (IPP). A 50% solution of the antiperspirant salt,such as Rehydrol II™ (aluminum chlorohydrex PG), in 190 proof ethanolwith the steric stabilizer at the desired ratio of steric stabilizer:antiperspirant salt is added to a preweighed round bottom flask. Theflask is gently agitated over a 45° C. water bath to dissolve the stericstabilizer and then attached to a rotary evaporator to remove theethanol. Evaporation is accomplished under vacuum, keeping the sampleflask in a water bath at 35°-50° C. Evaporation is continued until101-103% of the theoretical weight of the ethanol has been removed(note: excess loss is due to removal of either some water of hydrationor propylene glycol from the aluminum chlorohydrex PG), resulting in theformation of the adduct.

For precipitation of the adduct from an aqueous solution, a 25-30%aqueous solution of the antiperspirant salt and steric stabilizer isused, with the water being removed either by rotary evaporation, asdescribed above, or by lyophilization (freeze drying). Forlyophilization, the lyophilization flask is filled to no more than 40%of its total volume with the aqueous solution. The solution is thenfrozen as a shell, covering the inside surface of the flask, by rotatingthe flask in a dry ice-acetone bath. The frozen solution is thenlyophilized with no external heating for 18-24 hours.

The adduct and the appropriate amount of the carrier are transferred toan Oster glass mixing jar and blended with an Osterizer™ for a total of20 minutes. This results in the formation of an opaque dispersion. Theopaque dispersion is treated with the proper amount of water in anintensive mixing machine, such as a Vortex Genie, for about 10 minutesto develop transparency. The clarity of the dispersion can be describedaccording to the following rating scale.

CLARITY RATING SCALE

The following scale is based solely on visual appearance and is,therefore, subject to variability depending upon the observer.

    ______________________________________                                        Rating      Description                                                       ______________________________________                                        1           Opaque                                                            2           Opaque-to-translucent                                             3           Translucent                                                       4           Translucent-to-clear (or slightly hazy)                           5           Clear                                                             ______________________________________                                    

EXAMPLES 1-27 EXAMPLE 1

The following materials were treated according to the general proceduredescribed above:

Oleth-10/Rehydrol II™ (1.5/1 w/w) in 190 proof ethanol was employed togive adduct I. This adduct was dispersed into isopropyl palmitate (IPP)at a concentration of 25% solids, which is equivalent to 10% active APaluminum chlorohydrex PG (ACH-PG) and 15% Oleth-10. To obtain adispersion of substantial clarity (4 on the Clarity Scale), it wasnecessary to incorporate 3 parts of water per 100 parts of dispersion.

EXAMPLE 2

Adduct I of Example 1 was used to make a dispersion at 40% solids,equivalent to 16% active AP ACH-PG, in IPP. Five percent water was addedto give a dispersion with clarity=5.

EXAMPLE 3

Adduct I of Example 1 was used to make a dispersion at 50% solids,equivalent to 20% active AP ACH-PG in IPP. Three percent water was addedto give a dispersion with clarity=5.

EXAMPLE 4

Adduct I of Example 1 was used to make a dispersion at 75% solids,equivalent to 30% active AP ACH-PG in IPP. Three percent water was addedto give a dispersion with clarity=5.

EXAMPLE 5

Adduct I of Example 1 was dispersed into IPP/cyclomethicone (3/1 byvolume) at 50% solids equivalent to 20% active AP ACH-PG. Three percentwater was added to give a dispersion with clarity=5 (cyclomethicone is avolatile silicone commonly used in non-aqueous antiperspirants and othercosmetic systems).

EXAMPLE 6

Adduct I of Example 1 was dispersed into IPP/cyclomethicone (1/1 byvolume) at 50% solids equivalent to 20% active AP ACH-PG. Three percentwater was added to give a dispersion with clarity=5.

EXAMPLE 7

Adduct I of Example 1 was treated with 6 parts of water per 100 parts ofadduct by blending in an Osterizer™ until homogeneous to give a hydratedadduct. This hydrated adduct was dispersed into IPP at a concentrationof 50%, which is equivalent to approximately 20% ACH-PG, to give adispersion with clarity=5.

EXAMPLE 8

Oleth-10/Rehydrol II™ (1.75/1 w/w) in 190 proof ethanol was employed togive an adduct II which when dispersed into IPP at 55% solids which isequivalent to 20% active AP ACH-PG gave a clear dispersion (clarity=5)when treated with 2.5% water.

EXAMPLE 9

Oleth-10/Rehydrol II™ (1.25/1 w/w) in 190 proof ethanol was employed togive an adduct III which when dispersed into IPP at 45% solids=20%ACH-PG gave a substantially clear dispersion (clarity=4) when treatedwith 3% water.

EXAMPLE 10

Adduct III of Example 9 was dispersed into IPP at 56% solids=25% ACH-PGto give a clear dispersion (clarity=5) when treated with 4% water.

EXAMPLE 11

Oleth-10/Rehydrol II™ (1/1 w/w) in 190 proof ethanol was employed togive an adduct IV which when dispersed into IPP at 40% solids=20% ACH-PGgave a substantially clear dispersion (clarity=4) when treated with 4.5%water.

EXAMPLE 12

Adduct IV of Example 11 was used to make a dispersion at 50% solids,equivalent to 25% active AP ACH-PG, in IPP. Seven percent water wasadded to give a dispersion with clarity=5.

EXAMPLE 13

Adduct IV of Example 11 was used to make a dispersion at 60% solids,equivalent to 30% active AP ACH-PG, in IPP. Seven percent water wasadded to give a dispersion with clarity=5.

EXAMPLE 14

Oleth-10/Rehydrol II™ (0.5/1 w/w) in 190 proof ethanol was employed togive an adduct V which when dispersed in IPP at 30% solids=20% ACH-PGcan be used in a variety of conventional non-aqueous dispersion or stickformulations to produce smooth compositions that, unlike currentproducts, do not form a white chalky residue on the skin.

EXAMPLE 15

Oleth-20/Rehydrol II™ (1.5/1 w/w) in 190 proof ethanol was employed togive an adduct VI which when dispersed into IPP at 50% solids=20% ACH-PGgave a clear dispersion (clarity=5) when treated with 5% water.

EXAMPLE 16

Oleth-5/Rehydrol II™ (1.5/1 w/w) in 190 proof ethanol was employed togive an adduct VII which when dispersed into IPP at 50% solids=20%ACH-PG gave a clear dispersion (clarity=5) when treated with 5% water.

EXAMPLE 17

Ceteth-10/Rehydrol II™ (1.5/1 w/w) in 190 proof ethanol was employed togive an adduct VIII which when dispersed into IPP at 40% solids=16%ACH-PG gave a substantially clear dispersion (clarity=4) when treatedwith 4% water.

EXAMPLE 18

Nonoxynol-8/Rehydrol II™ (1.5/1 w/w) in 190 proof ethanol was employedto give an adduct IX which when dispersed into IPP at 50% solids=20%ACH-PG gave a clear dispersion (clarity=5) when treated with 4% water.

EXAMPLE 19

Sucrose stearate/Rehydrol II™ (1.5/1 w/w) in 190 proof ethanol wasemployed to give an adduct X which when dispersed in IPP at 50%solids=20% ACH-PG can be used in a variety of conventional non-aqueousdispersion or stick formulations to produce smooth compositions that,unlike current products, do not form a white chalky residue on the skin.

EXAMPLE 20

Laureth-4/Rehydrol II™ (1/1 w/w) in 190 proof ethanol was employed togive an adduct XI which when dispersed into IPP at 40% solids=20% ACH-PGgave an opaque-to-translucent dispersion (clarity=2) when treated with6% water.

EXAMPLE 21

Laureth-4/steareth-20/Rehydrol II™ (0.75/0.75/1 w/w/w) in 190 proofethanol was employed to give an adduct XII which when dispersed into IPPat 50% solids=20% ACH-PG gave a substantially clear dispersion(clarity=4) when treated with 5% water.

EXAMPLE 22

Laureth-23/trideceth-3/Rehydrol II™ (0.75/0.75/1 w/w/w) in 190 proofethanol was employed to give an adduct XIII which when dispersed intoIPP at 50% solids=20% ACH-PG gave a translucent dispersion (clarity=3)when treated with 5% water.

EXAMPLE 23

Oleth-10/aluminum zirconium tetrachlorohydrex PEG (1.5/1 w/w) in 190proof ethanol was employed to give an adduct XIV which when dispersedinto IPP at 50% solids=20% AP salt gave a clear dispersion (clarity=5)when treated with 4% water.

EXAMPLE 24

Oleth-10/Rehydrol II™ (1.5/1 w/w) in water was employed to give anadduct XV via rotary evaporation which when dispersed into IPP at 50%solids=20% ACH-PG gave a clear dispersion (clarity=5) when treated with5% water.

EXAMPLE 25

Oleth-10/aluminum chlorohydrate(ACH)/propylene glycol (1.5/1/0.33 w/w/w)in water was employed to give an adduct XVI via rotary evaporation whichwhen dispersed into IPP at 42.5% solids=15% ACH gave a clear dispersion(clarity=5) when treated with 5% water.

EXAMPLE 26

Oleth-10/ACH (1.5/1 w/w) in water was employed to give an adduct XVIIvia rotary evaporation which when dispersed into IPP at 50% solids=20%ACH gave a substantially clear dispersion (clarity=4) when treated with6% water.

EXAMPLE 27

Oleth-10/ACH/propylene glycol (1.5/0.75/0.25 w/w/w) in water wasemployed to give an adduct XVIII via lyophilization which when dispersedinto IPP at 50% solids=15% ACH gave a substantially clear dispersion(clarity=4) when treated with 3% water.

To confirm that sub-micron size particles of ACH had been produced,transmission electron microscopy was performed on replicas of both theadduct and clear dispersion of Example 3. The resulting micrographsrevealed the presence of approximately 0.05 micron particles that inmany cases appear to have a 0.015 micron coating due to the stericstabilizer, Oleth-10.

Although the invention has been described in terms of various preferredembodiments, one skilled in the art will appreciate that variousmodifications, substitutions, omissions, and changes may be made withoutdeparting from the spirit thereof. Accordingly, it is intended that thescope of the present invention be limited solely by the scope of thefollowing claims.

What is claimed is:
 1. A process for preparing a submicronantiperspirant adduct which comprises:(i) dissolving a mixture of analuminum-containing antiperspirant salt and a steric stabilizer in asolvent; (ii) followed by precipitation of the antiperspirant salt intothe steric stabilizer.
 2. The process of claim 1 wherein theprecipitation of the antiperspirant salt into the steric stabilizer isdone by (a) evaporation, (b) freeze drying or (c) the addition of anagent to cause precipitation, followed by filtration to recover theadduct.
 3. The process of claim 1 wherein the solvent is water or analcohol.
 4. The process of claim 3 wherein the alcohol is ethanol. 5.The process of claim 1 wherein the steric stabilizer is a nonionicsurfactant.
 6. The process of claim 5 wherein the surfactant is anethoxylated alcohol, a polyethoxylated alcohol, an alkyl phenolethoxylate, or a sucrose ester.
 7. The process of claim 6 wherein thealcohol is a fatty alcohol having between 12 and 18 carbon atoms.
 8. Theprocess of claim 6 wherein the ethoxylated alcohol is stearyl, cetyl, oroleyl alcohol.
 9. The process of claim 1 wherein the ratio of stabilizerto salt is about 0.1:1 to about 3:1.
 10. The process of claim 1 whereinthe ratio of stabilizer to salt is about 0.5:1 to about 3:1.
 11. Theprocess of claim 1 wherein the ratio of stabilizer to salt is about0.75:1 to about 2.5:1.
 12. The process of claim 11 wherein the ratio ofstabilizer to salt is 1:1 to 2.25:1.
 13. The process of claim 11 whereinthe ratio of stabilizer to salt is 1.25:1 to 1.75:1.
 14. The process ofclaim 1 wherein the aluminum-containing antiperspirant salt is analuminum sulfate, an aluminum chloride, an aluminum sulfocarbolate, oran aluminum chlorohydrate.
 15. The process of claim 1 wherein thealuminum-containing antiperspirant salt is an aluminum-zirconium salt.16. An adduct prepared by the process of claim
 1. 17. The adduct ofclaim 16 wherein substantially all of the adduct particles are less thanabout 0.4 microns.
 18. The adduct of claim 16 wherein substantially allof the adduct particles are less than about 0.15 microns.